1. Field of the Invention
The present invention relates to a security system including a cable which can be placed on a valve or switch handle to immobilize the same, a lock capable of retaining the cable, and a communications device which reports status of the lock to a remote monitoring station. The principal application of the invention is that of industrial safety in large facilities which handle piping systems having valves and electrical systems having switches. Oil refineries and other large scale fluid handling facilities, factories, large institutions, commercial and industrial facilities, and other facilities which require occasional shut down of piping systems and electrical power can benefit from the invention. The invention finds further utility in the field of security wherein unstaffed gates, ramps, doors, elevators, and similar transport devices must be locked and monitored remotely.
2. Description of the Prior Art
Large facilities having valves, switches, compactors, and other large scale material and energy handling systems require periodic maintenance. Maintenance typically requires that at least part of the material and energy handling systems be shut down to enable personnel to conduct necessary maintenance operations. In large scale piping systems, such as in oil refineries and chemical plants, manual valves are frequently employed to obstruct flow in piping. Such valves typically have handles which are rotated into the "closed" position. Electrical switches, such as safety switches, motor starters, circuit breakers, and custom control panels are similarly ordinarily provided with handles to shut off power.
Personnel charged with performing maintenance close valves and shut off power, where appropriate, and then undertake maintenance operations. In large scale facilities, the site of the actual work is frequently remote from the valves and electrical controllers which have been turned off. There exists a considerable hazard that someone not involved with the maintenance operation will come upon a valve, switch, or other controller, and restore the associated equipment to operative status.
This has potentially catastrophic consequences. Unexpected starting of even a single piece of equipment can cause severe injuries to a person who may have a limb in the path of moving or rotating parts. In the example of oil refineries and chemical plants, unexpected flow of combustible fluids can result in fires and explosions. Power turbines, pumps, and other rotating equipment, boilers, pressure vessel and tank closures, conveyors, hoists, and other equipment may be shut off with only ordinary controls, and thus become potentially sources of hazards should they suddenly be rendered operative. Obviously, the field of industrial safety requires safety procedures to prevent such occurrences.
Electrical switches such as safety disconnect switches and circuit breakers typically have provision for accepting padlocks enabling the switch to be locked in the "off" position. In the event that someone cuts through the shackle of the padlock, there is no way to annunciate the consequent change in condition to either personnel engaged in maintenance operations or to a central authority charged with oversight of operations.
The prior art has suggested security devices which detect unauthorized actions. U.S. Pat. No. 5,657,003, issued to Alfredo Fuentes on Aug. 12, 1997, describes a camera and computer based monitoring system which monitors a building wall. Should the wall undergo displacement of any type, images recorded by the camera are compared to data stored in the memory of the computer. Determination of a discrepancy triggers an alarm. By contrast, the present invention engages the object being monitored by direct contact with a cable, preventing the object from being moved to a predetermined position. The present invention further transmits an alarm signal should the object be freed from engagement. The cable is connected to its base apparatus at two ends. There is no corresponding structure in the device of Fuentes.
A bicycle lock is described in U.S. Pat. No. 4,663,611, issued to Chris W. Humphrey on May 5, 1987. The lock has an integral audible alarm which sounds if someone disables the lock. By contrast, the present invention sends a signal to a remote monitoring station to generate an alarm, rather than sounding an audible alarm. The present invention utilizes a locking cable as part of the electrical circuitry of the alarm. There is no corresponding structure in Humphrey.
A position signaling apparatus is shown in U.S. Pat. No. 5,617,072, issued to Dennis D. McNeal on Apr. 1, 1997. McNeal's apparatus comprises a sensing arm which projects from a motor vehicle. Unlike the present invention, the arm does not engage and immobilize an external object. Also, the arm does not connect to the apparatus at two points, as does a corresponding cable in the present invention.
U.S. Pat. No. 3,303,457, issued to Jan Assar .ANG.kesson on Feb. 7, 1967, sets forth a position sensor for sensing control rods of a nuclear reactor. There is no structure which engages and limits motion of the rods in the device of .ANG.kesson. By contrast, the present invention has a cable which engages and limits motion of a moving component of an environmental object.
U.S. Pat. No. 2,685,685, issued to Carl M. Lathrop on Aug. 3, 1954, describes a sensor and alarm for a pipeline pig. There is no structure which engages and limits motion of the pig in the device of Lathrop. By contrast, the present invention has a cable which engages and limits motion of a moving component of an environmental object.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.